This invention relates to a magnetic tape cartridge, and more particularly to a structure of a sliding door for opening and closing an opening for accommodating a leader pin and a structure for urging the sliding door in a magnetic tape cartridge comprising a cartridge casing, a single reel which is housed in the cartridge casing for rotation and around which a magnetic tape is wound, and the leader pin which is fixed to the leading end of the magnetic tape in order to draw out the magnetic tape from the cartridge casing.
As a recording medium for use in an external memory of a computer or the like, there has been known a magnetic tape cartridge comprising a magnetic tape wound around a single reel and a cartridge casing in which the reel is housed for rotation. Since the magnetic tape is used for storing data in a computer or the like and important information is stored on the magnetic tape, the magnetic tape cartridge is structured so that trouble such as tape jam does not occur and the magnetic tape is not accidentally drawn out.
A leader member (a leader pin in the present invention) is fixed to the leading end of the magnetic tape and the recording and reproducing apparatus is arranged to catch the leader member to draw out the magnetic tape from the magnetic tape cartridge and to rewind the magnetic tape into the magnetic tape cartridge. The leader pin is removably held inside an opening of the cartridge casing which is opened and closed by a sliding door. It is preferred that a lock member which firmly holds the both ends of the leader pin be provided so that the leader pin can be held in a predetermined position.
It is necessary to stabilize leader pin holding and releasing action of the lock member and sliding door opening and closing action in order to improve reliability of the magnetic tape cartridge.
That is, when the magnetic tape, which has been drawn out form the cartridge casing, is rewound around the reel and the leader pin is stored inside the opening of the cartridge casing, the lock member is brought into abutment against the leader pin to be deformed or displaced, and is returned to its original shape or position to be brought into engagement with the leader pin after the leader pin is moved to a predetermined rest position in which the leader pin is stored. In this case, it is preferred from the viewpoint of stabilizing the leader pin holding action of the lock member that the entrance part of the lock member which is first brought into contact with the leader pin be gently inclined. However, when the inclination of the entrance part of the lock member is gentle, the lock member is apt to be long and it becomes necessary to position the lock member to project toward the opening. The position in which the leader pin enters the cartridge casing (will be referred to as xe2x80x9cthe leader pin introduction positionxe2x80x9d, hereinbelow) slightly varies in the direction of width of the opening, and accordingly, the entrance part of the lock member must permit variation of the leader pin introduction position over a sufficient range. Also for the purpose of this point, it is preferred that the entrance part of the lock member be positioned to project toward the opening. When the entrance part projects toward the opening, there arises fear that the entrance part interferes with the sliding door.
It is preferred that the rest position of the leader pin be near to the opening since the leader pin holding member of the recording and reproducing apparatus which catches the leader pin is inserted through the opening to be brought into engagement with the leader pin. As a result, the lock member is disposed near to the opening and the sliding door. Accordingly, when drop impact acts on the magnetic tape cartridge, there is fear that the lock member comes to interfere with the inner surface of the sliding door to disable the sliding door from being opened, which deteriorates the reliability of the magnetic tape cartridge.
Further, when impact acts on the magnetic tape cartridge in the state where the leader pin is held in the rest position, e.g., while the magnetic tape cartridge is stored or being transported, with the magnetic tape slackened, the leader pin can be released from the lock member or can come to be held by the lock member in a wrong position deviated from the rest position. When the leader pin is once shifted from the correct rest position, there is no force acting on the leader pin to return it to the correct rest position, and the leader pin is kept deviated from the correct rest position. Accordingly, when the magnetic tape cartridge is subsequently loaded in a recording and reproducing apparatus, the leader pin holding member cannot hold the leader in the correct position, which causes trouble in operation of the recording and reproducing apparatus and deteriorates the reliability of the magnetic tape cartridge.
Further, it is necessary to provide on the sliding passage of the sliding door a spring member for urging the sliding door toward its closing position. However the sliding stroke of the sliding door is relatively long, and it is difficult to dispose a spring member conforming to such a long sliding stroke of the sliding door in a limited space, which makes it difficult to obtain desired spring characteristic.
Further, use of a coiled spring which is large in length/diameter ratio as the spring member gives rise to a problem that since the coiled spring is incorporated in the cartridge casing in a slightly compressed state, the coiled spring can buckle to spring back out of the predetermined position or to be pinched between upper and lower casing halves forming the cartridge casing, which deteriorates assembling facility of the magnetic tape cartridge.
In view of the foregoing observations and description, the primary object of the present invention is to provide a magnetic tape cartridge in which reliability of leader pin holding action of the lock member and reliability of the sliding door opening and closing action can be ensured.
The object of the present invention can be accomplished by a magnetic tape cartridge comprising a cartridge casing, a single reel which is housed in the cartridge casing for rotation and around which a magnetic tape is wound, the leader pin which is fixed to the leading end of the magnetic tape in order to draw out the magnetic tape from the cartridge casing, a lock member which is adapted to removably hold opposite ends of the leader pin inside an opening of the cartridge casing, and a sliding door for opening and closing the opening, wherein a recess is formed on the inner surface of the sliding door at least at a part opposed to the lock member.
It is preferred that the recess be formed so that the recess on the front end of the sliding door is closed by a wall surface of the cartridge casing when the sliding door is closed. The lock member may comprise upper and lower parts which are formed of a wire spring or a plate spring integrally with each other or separately from each other.
In accordance with the magnetic tape cartridge described above, by virtue of the recess formed on the inner surface of the sliding door at least at a part opposed to the lock member, interference of the lock member with the sliding door can be prevented and generation of failure in opening and closing the sliding door can be prevented. Further, freedom in the shape of the lock member is increased and the entrance portion of the lock member against which the leader pin is first brought into abutment can be gentle in inclination and sufficient in width, whereby leader pin holding action can be stabilized and reliability of the magnetic tape cartridge can be improved.
When the recess on the front end of the sliding door is closed by a wall surface of the cartridge casing when the sliding door is closed, dirt and dust are preventing from entering the cartridge casing and deterioration of recording quality can be prevented.
In a magnetic tape cartridge in accordance with another embodiment of the present invention, the inner surface of the sliding door is provided with a protrusion which prevents the leader pin from being released from the lock member in a state where the sliding is closed.
It is preferred that the height of the protrusion be set so that the distance between the top surface of the protrusion and the leader pin is not larger than the distance between the center of the leader pin and the contact point of the leader pin and the lock member as measured in the direction of movement of the leader pin toward the opening. Further, it is preferred that the protrusion be formed in a position where the protrusion cannot interfere with the lock member. The protrusion may be formed to extend toward the front end of the sliding door.
In accordance with the magnetic tape cartridge described above, by virtue of the protrusion formed on the inner surface of the sliding door, the leader pin can be prevented from being released from the lock members even if the leader pin is subjected to a force urging the leader pin away from the rest position, for instance, when the magnetic tape cartridge is dropped on the floor while it is stored or transported with the sliding door closed, whereby the leader pin can be surely caught in the correct position by the tape drive system and reliability of the magnetic tape cartridge can be improved.
In a magnetic tape cartridge in accordance with still another embodiment of the present invention, a coiled spring member extends through the sliding passage of the sliding door and a hole extending from the sliding passage in the direction in which the sliding door is opened along the mating surfaces of the upper and lower casing halves, and a plug is inserted into the hole to push the end of the coiled spring member remote from the sliding door so that the coiled spring urges the sliding door to its closing position.
It is preferred that the hole is formed by a pair of grooves which are respectively formed on the mating surfaces of the upper and lower casing halves of the side wall of the cartridge casing, in which the opening is formed, to extend from the rear end face of the sliding passage of the sliding door in the direction in which the sliding door is opened and open in a side wall of the cartridge casing which is adjacent to the side wall and extends in perpendicular to the side wall. Further, the groove may be formed on each of the mating surfaces or one of the mating surfaces. Further, it is preferred that the plug be provided with a resilient projection formed on the outer surface thereof and a recess which is adapted to be engaged with the projection and hold the plug in a predetermined position be formed on the inner surface of the recess. For example, a wedge-like projection may be formed on the outer surface of a shaft portion of the plug near the base end thereof and a slit may be formed in the shaft portion inside the projection to extend in the axial direction of the shaft portion so that the slit provides resiliency to the projection. Further, the plug may be provided with a large diameter portion which forms a shoulder between it and a shaft portion of the plug, and the hole may be provided with a large diameter portion for receiving the large diameter portion of the plug. Further, a projection may be formed on the outer surface of a shaft portion of the plug at the front end thereof and the front end portion of the shaft portion may be bifurcated to provide resiliency to the projection. It is preferred that a thin shaft portion which is inserted into the coiled spring member be provided to extend from the front end of the plug.
In accordance with the magnetic tape cartridge described above, since force urging the sliding door to the closing position is not generated until the plug is inserted into the hole, assembly of the cartridge casing and incorporation, of the sliding door and the spring member in the cartridge casing are facilitated.
In a magnetic tape cartridge in accordance with still another embodiment of the present invention, a spring member for urging the sliding door to its closing position is provided in the sliding passage of the sliding door with the spring member partly received in a recess formed in the sliding door.
It is preferred that the spring member is a corrugated plate spring. The recess may be formed on the inner side of the sliding door or the recess may be like a blind hole which opens in the rear end face of the sliding door. A recess may be formed on the sliding door by cutting away a part of the sliding door and the spring member in the form of a coiled spring may be received in the recess.
In a magnetic tape cartridge in accordance with still another embodiment of the present invention, a plurality of spring elements which are different in strength are arranged in series along the sliding passage of the sliding door to urge the sliding door to its closing position.
In a magnetic tape cartridge in accordance with still another embodiment of the present invention, a plurality of spring elements which are different in strength are arranged in parallel along the sliding passage of the sliding door to urge the sliding door to its closing position.
In a magnetic tape cartridge in accordance with still another embodiment of the present invention, a spring member for urging the sliding door to its closing position comprises a plurality of elastic ring members which are arranged in series along the door passage.
The spring member may comprise a plurality of helical elastic members.
In a magnetic tape cartridge in accordance with still another embodiment of the present invention, a spring member for urging the sliding door to its closing position comprises a corrugated wire spring having at least one coiled portion.
In a magnetic tape cartridge in accordance with still another embodiment of the present invention, a spring retainer plate which has upper and lower edges which are substantially parallel to the direction of sliding movement of the sliding door is mounted on the sliding door to extend in the sliding passage of the sliding door and a spring member in the form of a coiled spring for urging the sliding door to its closing position is contained in a space surrounded by the edge of the spring retainer plate and a wall defining the door passage.
It is preferred that the spring retainer plate be flexible.
In a magnetic tape cartridge in accordance with still another embodiment of the present invention, a pair of grooves are formed on opposite side walls of the sliding passage of the sliding door to extend in the direction of the sliding movement of the sliding door opposed to each other and a coiled spring member for urging the sliding door in its closing position is contained in the space formed between the grooves.
The grooves may be formed on an upper casing half or a lower casing half of the cartridge casing.
In a magnetic tape cartridge in accordance with still another embodiment of the present invention, a spring support rod which extends in the sliding passage of the sliding door in parallel to the direction of sliding movement of the sliding door is attached to the sliding door and a coiled spring member for urging the sliding door in its closing position is fitted on the spring support rod.
A spring receiving space which is wider than the space between opposite side walls of the sliding passage of the sliding door may be provided. The spring support rod may be provided with a flat surface on a side surface thereof and an axial hole into which the spring support rod is inserted may conform to the spring support rod in cross-sectional shape. A part of the coiled spring member may be received in a recess formed in the sliding door. The spring support rod may be provided at its free end with a projection for tacking the coiled spring member on the rod. The projection may be divided into a plurality of resilient pieces. The spring support rod may be provided with a pair of flat portions on opposite sides thereof, and an axial hole into which the spring support rod is inserted may be of such a diameter that permits insertion of the spring support rod without deformation of the resilient pieces. The coiled spring may be provided with a plurality of close winding portions. Further, the spring support rod may be formed integrally with the sliding door or formed separately from the sliding door.
In a magnetic tape cartridge in accordance with still another embodiment of the present invention, a door unit having a casing in which a sliding door for opening and closing the opening of the cartridge casing and a spring member for urging the sliding door to its closing position are incorporated is mounted on one side of the cartridge casing.
It is preferred that an engagement means which tacks the sliding door in a predetermined position overcoming the urging force of the spring member be provided between the casing of the door unit and the sliding door. The engagement means may comprise a pair of engagement projections formed on the top surface and the bottom surface of the sliding passage of the sliding door and a pair of engagement recesses formed on the upper and lower edges of the sliding door.
In a magnetic tape cartridge in accordance with still another embodiment of the present invention, a spring member for urging the sliding door to its closing position comprises a corrugated wire spring and the end portion of the wire spring is bent in the direction of width of the sliding door.
In a magnetic tape cartridge in accordance with still another embodiment of the present invention, a spring member for urging the sliding door to its closing position comprises a coiled spring having an annular portion which conforms to a rectangular or ellipsoidal cross-section of the sliding passage of the sliding door.
In a magnetic tape cartridge in accordance with still another embodiment of the present invention, a spring member for urging the sliding door to its closing position comprises a coiled spring extending in the direction of the sliding movement of the sliding door and a plate spring connected to at least one end of the coiled spring.
In accordance with the magnetic tape cartridges provided with the spring members described above, a spring member having a necessary stroke can be compactly incorporated and opening and closing of the sliding door can be stabilized, whereby reliability of the magnetic tape cartridge can be improved.